Delayed Language Development

Language Versus Speech

Language is a system of communication used within a group of individuals (e.g., all speakers of French). Across the approximately 6,500 languages spoken worldwide, each is characterized by a set of features across five domains: phonology, semantics (and the lexicon), syntax, morphology, and pragmatics. All languages have an inventory of sounds (phonology) and a set of meaningful words that form the basis for communication (lexicon and semantics). Languages have rules governing the combination of sounds into words, how words are ordered into sentences (syntax), and how words can be modified in sentences to convey finer-grained details (morphology), such as time (e.g., in English, adding the ed morpheme to kiss to indicate past tense versus adding the s morpheme for present tense).

Language also has social rules (pragmatics) explaining, for example, why speakers communicate one way with their friends and another with employers. Although domain features can overlap across languages (e.g., English and Spanish both use the sounds p, t, k, and g), no two languages have identical features, which is what uniquely differentiates Spanish from Portuguese, for example. From an early age, children begin learning their language’s features, and most will do so with ease. Individuals with a language delay might have difficulty learning the features with at least one, but possibly more, of the language domains. For example, difficulty with ordering words into sentences might indicate a syntax delay.

Speech, on the other hand, is the medium for verbalizing, or producing language. The primary component of speech needed to produce language is articulation. Articulation describes how accurately sounds in words are produced, and it correlates with how well a speaker is understood (also called speech intelligibility). Adequate speech depends on intact anatomical structures and physiological functioning. An abnormality in the speech production anatomical structures (e.g., a cleft lip or palate) may yield a speech delay or impairment. Importantly, a speech delay or impairment must specifically relate to articulation, voice, or the fluidity of speech, whereas a language delay or impairment refers to difficulty with any of the language domains described earlier.

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